1. Field of the Invention
This invention relates to a humidity measuring method and a hygrometer for electrically measuring humidity with high accuracy.
2. Description of the Prior Art
Heretofore, there have been employed a psychrometer, a hair hygrometer, a dew-point hygrometer, an absorption hygrometer and so forth for humidity measurement. The psychrometer is inexpensive and appreciably high in the accuracy of measurement, and hence is employed relatively widely; but this hygrometer requires constant wetting of a wet-bulb with water and therefore involves a water supply or replacement of a moisture absorbing gauze. The hair hygrometer is not satisfactory in the accuracy of measurement and the dew-point hygrometer involves cumbersome operations.
The absorption hygrometer is used for measurement of absolute humidity. In this case, a constant amount of air is passed through a U-shaped tube containing phosphorus pentoxide (P.sub.2 O.sub.5) to entirely absorbe water vapor in the air by the phosphorus pentoxide and an increase in the mass of the phosphorus pentoxide is measured; since the increase in the mass corresponds to the water content in the air, the absolute humidity is obtained. But the absorption hygrometer is defective in that its measuring operation is complex.